Facebook has been toying with the idea of video ads for users' News Feeds for a few years, though despite its limited experiments, the social media giant hasn't enabled them for all users yet. That may change soon, as the company has announced its testing a new auto-play video ad feature.

As a publicly traded company, Facebook is under pressure to perform for its shareholders, which means enabling ads that will engage users and generate more revenue. But as a social media site that began ad-free, the company also has to be careful about how it much it allows marketers to interfere with its users' News Feeds.

As of Tuesday, Facebook has announced that it's testing a format for advertisers that it thinks might be able to achieve that delicate balancing act. Just like the video system for user-created and shared content that it has been testing since September, Facebook is looking at a video ad system that auto-plays in users' News Feeds, without blasting them with sound or taking over the page.

According to Facebook's newsroom release, the social media giant is beginning to test a video viewing format for advertisers that a "small number of people will see," at least during the experimental phase. The first video ad will be a trailer for the Summit Entertainment film Divergent - a pretty safe place to start, considering how many trailers are shared by users on Facebook already.

There's a few rules about how video ads will appear under this system.

First, the video will appear in the user's News Feed in the same place posts appear, and it will already be playing as you scroll down to it, unless you're on mobile without a WiFi connection. In that case, the video will only appear if it was downloaded on a WiFi connection prior - Facebook is emphasizing that loading video advertising content is designed not to touch anyone's data plan allotment.

Second, while the video will auto-play like videos shared by users in the News Feed, advertising videos will be muted. Only after you click or tap and play in full screen, will the sound for that video play as well.

Finally, at the end of the video advertisement, two additional video ads will be shown in a "see also"-type carousel. Users are (of course) welcomed to "Like," "Comment," or "Share" the marketing material if they want.

Here's Facebook's example of the Divergent ad in a mobile news feed.

If a user doesn't want to see the video advertisement, they can just continue scrolling down the news feed to ignore it.

In this way, Facebook hopes to satisfy some of the marketers' desires, while keeping the citizens of Facebook from revolting over too many advertisements. And while advertisers might bemoan the need to refit their content to get the message out even when muted (notice that while the Divergent trailer had sound effects, the voiceover was replaced by text), Facebook has a lot of eyes to sell them, and they're likely to be happy just to have any video ads on the billion-person social network: As TechCrunch reported late last week, Facebook reaches more 18-24 year olds (the most coveted demographic) during primetime than any other major TV network.